So what, exactly, does the State Department do? dg has done an excellent job in describing its structure, but its function is another matter entirely. Let's look at the people involved in the State Department, starting with its backbone:

In the field, many FSO's spend most of their time in shuttle diplomacy, meeting with officials of their host government to explain what the United States want, using the necessary kowtowing procedures that an untrained American agent wouldn't. When coups or civil unrest are going on, as they are going on in a quarter of the world at any given moment, an FSO's job can be especially difficult. More on that later. (Other overseas FSO's have similar jobs to their desk jockey counterparts back home.)

Ambassadors are appointed directly by the President, and come in two basic varieties. Most American ambassadors in the developing world are aging FSO's who have been promoted from the line of duty. Virtually all American ambassadors in the developed world, on the other hand, are either friends of, or major contributors to the last campaign of, the sitting President (Terry McAuliffe and James C. Hormel are two infamous examples from the Clinton administration).

This makes sense, if you think about it. Ambassadorships are a great patronage gift after a successful campaign: who wouldn't want to be the U.S. Ambassador to France, Japan, or Germany? The intergovernmental links between these countries are so strong that the State Department doesn't have to do much, anyway, except organize white tieballs. Islands in the Caribbean are also popular ambassadorships for presidential benefactors: think of it as a paid vacation in Jamaica.

At the same time, no wealthy Americans want to be sent to Nicaragua or Zimbabwe, and even if they did go there, they wouldn't have the slightest clue about how to deal with the locals. So the elder FSO's are excellent candidates for these tough jobs, as they already have a great deal of experience in foreign relations and diplomacy.

Some other outsiders with specialized knowledge occasionally receive ambassadorships under extraordinary circumstances: the only one I can name off the top of my head is Edwin O. Reischauer.

My inspiration for noding this is a spur of the moment one. Today, we had a former distinguished FSO turned ambassador, who is now a dean at our university, speak to our foreign policy class. He delivered a mundane, professorial lecture for half an hour or so, and then answered a couple of equally mundane questions before getting one from out of nowhere. One girl in the back of the room asked, in paraphrase, "What was the most difficult decision you had to make as an FSO?"

The old dean thought for a moment about that, and then answered (also in paraphrase):

I suppose it was when I was working at the embassy in Liberia. Back then, there was a civil war going on. They said that 200,000 people died in the war, but nobody really knows to this day: you could say 50,000 or 500,000 and still prove that your numbers are right.

The military didn't want to intervene to stop the violence, and so I had to go to the leaders and tell them that the Marines wouldn't be coming to save the day. Now, Liberia was founded by freed slaves, and they've always been close to the United States. One of the men burst out in anger, saying—if you'll excuse the term, because this was the term he used—that we thought the Liberians were a bunch of worthless niggers.

The rebel forces were only four days away from the capital, and the leaders knew that once they were found, they would be killed. We had to sign their death warrant.

Incidentally, before my next class, I was flipping through the school paper, and happened across an article about foreign graduate students protesting a new INS fee that was leaving financial holds on their accounts. The same dean who spoke to us was quoted in the article as saying there wasn't much that could be done about it.